The present invention relates to copying apparatus utilizing a photosensitive member which has a photoconductive layer for forming electrostatic latent images.
Generally speaking in copying apparatus utilizing a system for forming electrostatic latent images, an electric charge is uniformly made, in the dark or with exposure to light, on a photosensitive member having a photoconductive layer coated on an electric conductive base, or having a transparent insulating layer coated on the photoconductive layer, on whose surface an electric potential is generated. An area of the thus generated surface electric potential is removed by making use of any one of the methods which are already publicly known, such as the imagewise exposure method, and thereby an electrostatic latent image is formed. The electrostatic latent image is made visible by already known methods using toner or developer; the image density of the visible image is dependent on the surface electric potentials of a photosensitive substance which forms electrostatic latent images. In this connection, in copying apparatus utilizing any one of the known systems for forming electrostatic latent images, it is always desirable for obtaining good copy images to provide satisfactory fixed surface electric potentials on the photosensitive substance to be used, in accordance with the characteristic of the electric charge thereof.
However, copying itself can be achieved only by the proper correlative operations of both process measures and photosensitive substance. Additionally, those photosensitive substances will have a scattering of characteristics of the electric charge in every lot of manufacture or in every individual cause, more particularly with a Se photosensitive substance. Therefore to obtain fine copy images having a proper density reproductivity, one must adjust the copying apparatus so as to maintain the best suitable conditions for the electric charge on the photosensitive substance. Normally, to make an adjustment of the characteristics of electric charge on an individual photosensitive substance, such as the adjustment of electric current for electric charging, it is necessary to use a measuring apparatus such as an ampere meter. Moreover such adjustments are often incorrect with the dangers arising therewith, because such adjustments deal with high tension voltages about 4-6 kilovolt. Furthermore; the adjustment takes much time.